Current surge suppression systems have been developed to protect equipment from voltage transients on one side of a three-phase power supply bus used in industrial settings such as in plants, factories, or other large scale systems. In one known voltage surge suppressor, three single-phase transformers are provided with terminals that are each connected through a fused disconnect to a respective single-phase power supply on the power-supply bus. This surge suppressor protects against voltage transients, which can severely damage or destroy equipment connected to the effected three phase circuit or can cause power outages throughout the plant. The surge suppressor circuit operates as a surge and fault protector for any equipment on the power bus. This surge suppressor system is usable with 480 volt distribution systems powered by a 2000 to 3000 kVA ungrounded delta power transformer that feeds approximately 1000 ft of bus duct, so as to generally have about 1 to 3 Amperes of charge current. This charge current may generally be just over 2 Amperes by actual amperage determined by readings in the field, wherein the variations are due to the lengths of the feeder cable and bus duct as well as the number and size of the electric motors and power factor correction capacitors operating at any given time. More typically, resistance grounding circuits constantly bleed this charge to ground to help prevent grounding problems. The known surge suppressor is connected to the bus bars and does not bleed this energy to ground, but uses this charge energy to help stabilize and balance the phase voltages to ground.
This known surge suppressor is installed in and protects equipment connected to a power supply bus at the facility level. However, there is a need for a surge suppressor system for medium and high voltage electrical systems on the grid located outside of and remote from an industrial bus bar power supply system.
A power grid is comprised of many components that are generically described as generators, transformers, transmission and distribution wires and controls. Generators are driven by many forms of energy such as coal, natural gas, nuclear fission, hydro, solar and even wind to name a few. Once power is created at a relatively low voltage around 6,000 volts it is stepped up to high voltage (often in the hundreds of thousands) using large power transformers (LPTs) which allow the electricity to be more effectively delivered over miles of high tension (transmission) wires. Once the electricity reaches the general area where it will be used it is then stepped back down closer to the final voltage at sub/distribution stations. Distribution lines carry near-low voltage electricity on roadside power poles or underground to the final transformer before being delivered into buildings for use.
The present invention is a surge suppressor system that improves upon existing phase adder circuit products, is designed to provide grid-level protection to residences and industrial facilities prior to delivery of the power to these structures so they can withstand higher voltages, provide monitoring and communication from remote settings, and provide more robust installation platforms, and configures the system of surge protection devices in parallel to protect grid level applications on both sides of a power system where the need exists to step power either up or down.
On a medium or high voltage system, the current invention would be configured to handle large and rapid energy “drain offs”, prevent interference from high voltage/high magnetic flux, allow remote performance maintenance, and increase protection, as required, from physical attacks and severe over voltages. When the invention is installed in parallel with critical grid infrastructure, the components of the grid are protected against:
Transients: An impulsive transient is what most people are referring to when they say they have experienced a surge or a spike. Many different terms, such as bump, glitch, power surge, and spike have been used to describe impulsive transients. Causes of impulsive transients include lightning, poor grounding, the switching of inductive loads, utility fault clearing, and Electrostatic Discharge (ESD). The results can range from the loss (or corruption) of data to physical damage of equipment. Of these causes, lightning is probably the most damaging. The surge suppressor devices of the current invention provide grid-level protection against such transients.
Interruptions: An interruption is defined as the complete loss of supply voltage or load current. The causes of interruptions can vary but are usually the result of some type of electrical supply grid damage, such as lightning strikes, animals, trees, vehicle accidents, destructive weather (high winds, heavy snow or ice on lines, etc.), equipment failure, or a basic circuit breaker tripping. While the utility infrastructure is designed to automatically compensate for many of these problems, it is not infallible.
Sag/Under-voltage: A sag is a reduction of AC voltage at a given frequency for the duration of 0.5 cycles to 1 minute's time. Sags are usually caused by system faults and are also often the result of switching on loads with heavy startup currents.
Swell/Over-voltage: A swell is the reverse form of a sag, having an increase in AC voltage for a duration of 0.5 cycles to 1 minute's time. For swells, high-impedance neutral connections, sudden (especially large) load reductions, and a single-phase fault on a three-phase system are common sources.
Frequency Variations: There are all kinds of frequency issues from offsets, notching, harmonics, and inter-harmonics; but these are all conditions that occur largely in the end user's power system. These variations happen because harmonics from loads are more likely in smaller wye type systems. The high frequency variations that may lead to massive interconnected grid failure would come from the sun or enemy attack. Damage to only a few key infrastructure components could result in prolonged blackouts and collateral damage to adjoining devices. Solar flares are natural occurrences that vary in severity and direction. This “solar weather” is sent out from the surface of the sun throughout our solar system in all directions. These flares contain large amounts of magnetic energy and depending on how they hit the earth can cause component damage on the surface or by temporarily changing the properties of the planet's magnetic core. Either way, a direct hit of large proportion could cause equipment failure and black out entire regions. Electromagnetic Pulses (EMP) can be used in similar fashion but directed by enemy combatants in the form of a high altitude nuclear explosion. A well-executed detonation over Cincinnati, Ohio could black out 70% of the American population. Damage to large power transformers or generators could take months to repair. The high frequency disturbance of nuclear explosions can destroy unprotected components much like an opera singer's voice can break a glass. The magnitude of each disturbance may depend on the source but each can be mitigated effectively through the use of a phased voltage stabilization system such as the invention.
Current surge suppression technology may attempt to address these disturbances on the facility side of the power distribution system, so as to directly protect equipment in a facility, and also at a grid level but these technologies possess drawbacks in protecting against these disturbances.
As one example of a known surge suppression technology, capacitors are thin conductors separated by even thinner layers of insulation. Capacitors have a design rating for current and voltage. If this rating is not exceeded they will typically operate for 10 to 15 years. One high voltage spike may (and generally will) cause catastrophic failure of capacitors. In factories with 4,000 power factor correction capacitors, it is not uncommon to have 300 to 500 capacitors fail each year due to high harmonic current or high voltage spikes.
In another example, SPD (Surge Protective Devices) are solid state devices constructed in various sizes. Like capacitors, their ratings are also in current and voltage. When the MOV (Metal Oxide Varistor) is hit with many low-level voltage spikes it degrades, and the “clamping voltage” will rise as the MOV breaks down, allowing the clamping voltage to continue to rise until it no longer protects the equipment it was installed to protect. When a voltage spike hits the MOV above the rated voltage, it starts to conduct thousands of amps to ground, causing noise on the ground system and very high heat within the SPD. If the event is longer than a few millionths of a second, the MOV could be destroyed, and therefore would no longer protect the equipment it was installed to protect.
Further, Faraday cages have been used for many years to house and protect computer hardware and sensitive data in factories, as well as some government and military buildings. They recently have been touted as a solution to solar flares, lightning and EMP pulse issues. However, most buildings are not built within a metal enclosure and it is difficult and expensive to properly design and build these enclosures. Most automobiles, trucks, trains and planes are totally enclosed by metal, but they offer no protection from any of these events. By design, the metal enclosure must have a suitable solid ground connection as it relies heavily on enclosing and shielding the sensitive electrical equipment and removing the energy by draining it to ground. The power company uses the Faraday cage design in some of their grid tie substations. They are extremely large and expensive.
The greatest threat to the grid/LPTs is the presence of an electromagnetic pulse (EMP) or geomagnetic disturbance (GMD), the latter would originate as a solar flare and the prior would be from enemy weaponry. Either threat could cause an overworked LPT to be saturated with power and cause the transformer to burn out. With an EMP, saturation could happen in less than a second so detection systems are worthless.
GMD is slower to cause damage so detection systems could reduce the load on a transformer which could allow it to ride out the GMD incident. This brown out or temporarily blacked out condition could last minutes, hours or days depending on the severity of the solar storm. In the case of the 1869 Carrington Event the Earth was pummeled with solar magnetic energy for nearly a month. While the grid could survive such an event if properly managed it would hardly be well received by citizenry to be without power that long.
Simply, Large Power Transformers cannot be protected with old technology like Faraday Cages. The hundreds of miles of wire that connect the LPT to sub stations way down the line act like antennae and harvest EMP with such efficiency that the Faradays would have no value. Surge protecting devices are not fast enough to arrest an EMP which occurs in a millionth of a second or handle the massive electron flow that occurs at the transmission level without allowing current bleed through to the LPT which would ultimately have the same effect as an unprotected system. Grounding systems would try to route surplus current from an EMP to earthen ground probes or mats but that excess energy would likely find its way back into the power system through the ground bus and result in burnout as well.
The present invention relates to a system of surge suppressor units connected at multiple locations on the grid to provide grid level protection against various disturbances before such disturbances can reach or affect facility level equipment. The effect of the invention is significant for protecting grid level applications. With the unique application and design of the present application, the surge suppressor units of the present invention would effectively prevent major voltage and current spikes from impacting the grid. In addition, the surge suppressor units included various integration features which provide diagnostic and remote reporting capabilities required by most utility operations. As such, the surge suppressor units protect the grid level components from major events such as natural geomagnetic disturbances (solar flares), extreme electrical events (lightning) and human-generated events (EMPs) and cascading failures on the power grid. The invention also provides significant protection against arc flashes and reduces voltage harmonics that exists in “normal” grid operations.
The reporting features of the inventive surge suppressor unit are also unique to protecting medium and high voltage systems that are often in remote or isolated settings. Unlike devices designed to protect local low voltage equipment and infrastructure, real time diagnostic reporting from the surge suppressor unit is critical to ensure it is working effectively and providing the continuous protection needed to protect power systems like the US power grid.
As discussed, various known technologies (such as MOVs, Faraday cages, even similar devices designed with fused disconnects) attempt to also correct voltage imbalances. These devices either do not provide the scalability to the voltage requirements at the grid level or “burn out” when significant voltage is applied. These technologies also do not provide reporting, remote diagnostics, or protection from ancillary dangers such as arc flashes or localized voltage overflow. The surge suppressor system of the present invention provides each of these benefits and is also completely scalable for various grid level applications.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.